Reconfigurable Hybrid Power Train

ABSTRACT

A multi-mode hybrid drive train offers selective operation in any one of series, parallel, and power split modes. The multi-mode hybrid drive train includes two planetary gear sets and a collection of specifically placed brakes and clutches relative to those gear sets. The first planetary gear train includes a power input for receiving power from a primary rotational power source, as well as a first sun gear, first carrier and first ring gear. The second planetary gear train similarly includes a power input as well as a second sun gear, a second carrier connected to a final drive, and a second ring gear. A first motor is linked to the first sun gear and a second motor is linked to the second sun gear such that selective activation of the clutches, brakes, and motors places the multi-mode hybrid drive train in a selected mode of operation.

TECHNICAL FIELD

This patent disclosure relates generally to power transmission systemsand, more particularly to a reconfigurable power transmission systemthat provides multiple modes of operation.

BACKGROUND

In any power transmission system for providing machine movement, it isimportant to efficiently transfer power from a power source to a drivenimplement such as a wheel, track, or other ground-engaging system. Withrespect to electrical/hybrid drive trains, various transmission formatshave arisen to provide this function, each having distinct advantages,as well as potential disadvantages relative to the others. Such formatsinclude for example series, parallel and power split formats.

Unfortunately, the formats are generally mutually exclusive, and it hasbeen necessary to forgo the advantages of all but one format in anygiven implementation. As a result designers have been required to selectthe format with the most advantages for a particular implementation,with the understanding that the selected format will in some instancesbe disadvantageous. For example, a format that provides efficient highspeed operation may be inefficient or ineffective during a differentmode of operation such as start up.

Thus, although electrical/hybrid machines have in general been verysuccessful, the available drive trains have been inadequate to fullyrealize the benefits of these power systems. The disclosed principlesprovide a mechanism for overcoming the noted deficiencies as will beappreciated from the following description.

SUMMARY

In an aspect of the disclosed principles, a multi-mode hybrid drivetrainis provided for selective operation in any one of series, parallel, andpower split modes. The multi-mode hybrid drive train includes twoplanetary gear sets and a collection of specifically placed brakes andclutches relative to those gear sets. The first planetary gear trainincludes a power input for receiving power from a primary rotationalpower source, as well as a first sun gear, first carrier and first ringgear. The second planetary gear train similarly includes a power inputas well as a second sun gear, a second carrier connected to a finaldrive, and a second ring gear.

For configuration, the multi-mode hybrid drive train includes a firstclutch for selectively clutching the first carrier to the second carrierand a second clutch for selectively clutching the first sun gear to thesecond ring gear. It further includes a first brake for selectivelybraking the first carrier, a second brake for selectively braking thefirst sun gear, and a third brake for selectively braking the secondring gear. A first motor is linked to the first sun gear and a secondmotor is linked to the second sun gear such that activation of theclutches, brakes, and motors in a first combination places themulti-mode hybrid drivetrain in a series mode of operation, activationof the clutches, brakes, and motors in a second combination places themulti-mode hybrid drive train in a parallel mode of operation, andactivation of the clutches, brakes, and motors in a third combinationplaces the multi-mode hybrid drive train in a power split mode ofoperation.

Further aspects and features of the disclosed principles will beappreciated from the following detailed description and the accompanyingdrawings, of which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a reconfigurable power transmissionaccording to an embodiment of the described principles;

FIG. 2 is a schematic view of the reconfigurable power transmission ofFIG. 1, showing clutch, brake, and electrical inputs/outputs arranged toprovide a series mode configuration;

FIG. 3 is a schematic view of the reconfigurable power transmission ofFIG. 1, showing clutch, brake, and electrical inputs/outputs arranged toprovide a parallel mode configuration;

FIG. 4 is a schematic view of the reconfigurable power transmission ofFIG. 1, showing clutch, brake, and electrical inputs/outputs arranged toprovide an input CVT configuration;

FIG. 5 is a schematic view of the reconfigurable power transmission ofFIG. 1, showing clutch, brake, and electrical inputs/outputs arranged toprovide a compound CVT configuration; and

FIG. 6 is a chart illustrating actuation settings correlated to variousoperational modes in an embodiment of the disclosed principles.

DETAILED DESCRIPTION

In overview, this disclosure relates to power transmission inelectrical/hybrid systems, and the disclosed principles provide adrivetrain that may be reconfigured in real-time through the engagementor disengagement of multiple control units (brakes and clutches), togenerate various drive train configurations including series, paralleland CVT. In one embodiment, the system employs two clutches, threebrakes and two planetary gear trains to provide reconfigurability aswell as to provide multiple operational modes such as neutral,electrical reverse, engine start/stop, extended driving duration, etc.

Turning to the figures, FIG. 1 is a schematic view of a reconfigurablepower transmission according to an embodiment of the describedprinciples. As can be seen, the drivetrain 100 of FIG. 1 takes a powerinput from an engine 101 or other type of primary power source(hydraulic motor, etc), as well as taking power from or providing powerto two motor/generator units including a first motor/generator unit 103and a second motor/generator unit 105. The output of the drivetrain 100is provided at a final drive 107, e.g., to drive a ground engagingtrack/wheel/sprockets, etc.

The disclosed drive train 100 includes a number of transmission elementsand actuators to provide drive and reconfiguration functions. Theseinclude a first planetary gear set 109 and a second planetary gear set111, as well as a first brake (B1) 113, a second brake (B2) 115, and athird brake (B3) 117. The system 100 further includes a first clutch(C1) 119 and a second clutch (C2) 121. The engine 101 provides a powerinput to the ring gear R1 of the first planetary gear set 109 while thecarrier C1 of the first planetary gear set 109 is clutched via the firstclutch 119 to the carrier C2 of the second planetary gear set 111 and tothe final drive 107. The carrier C1 of the first planetary gear set 109is also linked to the third brake 117. The sun gear S1 of the firstplanetary gear set 109 is linked to the first brake 113 and the firstmotor/generator 103, as well as being clutched via the second clutch 121to the ring gear R2 of the second planetary gear set 111. The ring gearR2 of the second planetary gear set 111 is also linked to the secondbrake 115. The sun gear S2 of the second planetary gear set 111 islinked to the second motor/generator 105.

Selective actuation of the first brake 113, second brake 115, thirdbrake 117, first clutch 119 and second clutch 121 is used to reconfigurethe drive train 100 to correspond to a series, parallel or CVT format orconfiguration. FIG. 2 illustrates an example of a series modeconfiguration. In particular, the illustrated drive train 200 isconfigured such that the engine 201 drives the first motor/generator203, which is acting as a generator, through the first planetary gearset 209. This generates power for use by the second motor/generator 205,which is acting as a motor. A motor controller 230 may be used to managethe transfer of energy to the second motor/generator 205. The secondmotor/generator 205 in turn drives the final drive 207 via the secondplanetary gear set 211.

In order to provide this configuration, the second brake 215 and thethird brake 217 are engaged. In this way, the input to the firstmotor/generator 203 (i.e., the output of the first planetary gear set209) is directly proportional to the speed of the engine 201 and theoutput of the second planetary gear set 211 is directly proportional toits input, i.e., to the speed of the second motor/generator 205. Thus,in this configuration, the generation and use of electrical power occurin series, with no direct mechanical link between the engine 201 and thefinal drive 207.

As noted above, the disclosed drive train may also be configured toprovide parallel operation, i.e., wherein the final drive is driven byone or both of an engine and an electric motor operating in parallel.FIG. 3 illustrates the reconfigurable power transmission of FIG. 1,showing clutch, brake, and electrical inputs/outputs actuated so as toprovide a parallel mode configuration. In the illustrated configuration,the first clutch 319, the first brake 313, and the second brake 315 areactuated. In particular, the first clutch 319 links the carrier C1 ofthe first planetary gear set 309 to the final drive 307 and to thecarrier C2 of the second planetary gear set 311. The first brake 313brakes the sun gear S1 of the first planetary gear set 309 while thesecond brake 315 brakes the ring gear R2 of the second planetary gearset 311.

As a result of these actuations, the engine 301 provides power to thefinal drive 307 at a ratio set by the gear ratios of the first planetarygear set 309 while the second motor/generator 305 is linked to the finaldrive at a ratio set by the gears of the second planetary gear set 311.In this way, the second motor/generator 305 may either receive powerfrom the engine 301 for storage in energy storage system 340 or drawenergy from the energy storage system 340 and provide power to the finaldrive 307 in parallel with the engine 301.

FIG. 4 illustrates another configuration of the disclosed system,wherein the system is configured via selective actuation of braking andclutching mechanisms to operate in an input CVT configuration. In thisconfiguration 400, the second brake 415 and first clutch 419 areactuated, respectively holding the ring gear R2 of the second planetarygear set 411 stationary and clutching the carrier C1 of the firstplanetary gear set 409 to the carrier C2 of the second planetary gearset 411 and to the final drive 407. In this configuration, the power,speed, and rotational direction of the final drive 407 are set by thefirst motor/generator 403 and the second motor/generator 405. Thus, thisconfiguration provides a continuously variable output based on thecontrol of two parallel inputs (the motor/generators).

In a slightly different configuration, the system acts as a compoundCVT, wherein the output characteristics are set by both motors, butwherein the effect of one of the motors is magnified by mechanicalcompounding. This configuration is illustrated in FIG. 5. As can be seenthis configuration is created by the actuation of the first clutch 519and the second clutch 521, while leaving the three brakes unactuated.This configuration is similar to the parallel input CVT configurationshown in FIG. 4.

However, rather than holding the ring gear R2 of the second planetarygear set 511 stationary, this gear is instead clutched to the firstmotor/generator 503 via the second clutch 521. In this way, the rotationof the first motor/generator 503 is transferred to both the sun gear S1of the first planetary gear set 509 and the ring gear R2 of the secondplanetary gear set 511, providing a compounding effect with respect tothe rotation of the first motor/generator 503.

Although the foregoing description discusses specific motor and enginetypes, the disclosed principles are also applicable with respect toother types of rotary machines. For example, the engine 101 may be anyone of a number of fuel converter devices (e.g., gasoline engine, dieselengine, turbine engine, jet engine, etc.), or may be an electricalmotion device or hydraulic motor. With respect to the firstmotor/generator 103 and second motor/generator 105, these were discussedabove as being electrical motors/generators, but may be any other typeof rotary power providing/generating device including for examplehydraulic pump motors, pneumatic pumps (e.g., air compressors)/motors(e.g., air motors), etc.

In overview, and referring again to FIG. 1, it will now appreciated thatselective actuation of the first brake 113, second brake 115, thirdbrake 117, first clutch 119 and second clutch 121 will allow thedisclosed transmission to operate in a selected mode optimized forcurrent conditions. The actuation of various controls to provideexpected modes of operation within these configurations will be brieflyset forth for the convenience of the reader.

The chart 600 of FIG. 6 sets forth the actuation settings usable toachieve various operational modes. In particular, each mode isassociated with an actuation mode for each of the first brake 113 (B1),second brake 115 (B2), third brake 117 (B3), first clutch 119 (C1) andsecond clutch 121 (C2). The chart 600 also sets forth the status of eachmotor in each mode. The motor modes include “off,” generator (“g”),motor (“m”) and motor-in-reverse (“m(rev)”).

The modes described in the chart 600 include parking (engine off),parking (engine on), neutral, engine start (parking), engine start(neutral), forward (low speed), input eVT, forward (high speed),compound eVT, reverse (electrical powered reverse), reverse (serieshybrid reverse), eDry 1 (driving on one motor), and eDry 2 (driving ontwo motors). It will be appreciated that this is an exemplary list ofmodes, and that other modes may be employed as well within the describedprinciples.

While manual activation of the clutches and brakes of the hybridtransmission is possible, the clutches and brakes are controlled by acontroller in an embodiment of the described principles. This isespecially useful in modes where simultaneous control of the motors andengine is also required. The controller may be a dedicated controller ormay be a portion of a machine controller, engine controller, ortransmission controller. In any case, the controller is processor-drivenand operates by reading computer-readable instructions, including datawhere appropriate, from a computer-readable medium, andcomputer-executing the instructions so read. The computer-readablemedium is a tangible medium, and may be a volatile or nonvolatilememory, RAM, ROM, flash drive, optical drive, magnetic drive, etc., asappropriate in a given implementation of the disclosed principles.

The controller operates by receiving a user or other selection of amode, and by responsively activating the necessary clutches and/orbrakes to implement the selected mode. While in a given mode, thecontroller also coordinates the motor/generators and the engine asappropriate to carry out user or machine commands.

INDUSTRIAL APPLICABILITY

The described system and method are applicable to machines and deviceswherein it is desirable to transfer power in a controlled manner from arotational power source to a ground engaging mechanism such as wheels ortracks. Typically, usage environments include construction, industrialmachines and associated equipment. The disclosed principles provide apower transmission that is fully reconfigurable to selectively operateas any one of a number of transmission types depending upon the presentneeds of the system in which the transmission is used.

In this context, the disclosed system facilitates reconfiguration viaselective actuation of individual brakes and clutches to operate in aseries, parallel, input CVT, or compound CVT configuration. Moreover,within these modes, others of the brakes and/or clutches may beactuated, and the motors appropriately controlled, to provide specifictypes of operation. For example, selective actuation of these componentsallows a parking operation with the engine on, a parking operation withthe engine off, a neutral operation, forward low speed operation,forward high speed operation, and so on.

It will be appreciated that the foregoing description provides examplesof the disclosed system and technique. However, it is contemplated thatother implementations of the disclosure may differ in detail from theforegoing examples. All references to the disclosure or examples thereofare intended to reference the particular example being discussed at thatpoint and are not intended to imply any limitation as to the scope ofthe disclosure more generally. All language of distinction anddisparagement with respect to certain features is intended to indicate alack of preference for those features, and not to entirely exclude suchfrom the scope of the disclosure unless otherwise indicated.

Recitations of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context.

1. A multi-mode hybrid drive train for selective operation in any one ofseries, parallel, and power split modes, the multi-mode hybrid drivetrain comprising: a first planetary gear train having a power input forreceiving power from a first motor/generator unit, the first planetarygear train having a first sun gear, first carrier and first ring gearand a second planetary gear train having a power input for receivingpower from a second motor/generator unit, the second planetary geartrain having a second sun gear, a second carrier connected to a finaldrive, and a second ring gear; a first clutch for selectively clutchingthe first carrier to the second carrier and a second clutch forselectively clutching the first sun gear to the second ring gear; afirst brake for selectively braking the first carrier, a second brake orselectively braking the first sun gear, and a third brake forselectively braking the second ring gear; and a first motor linked tothe first sun gear and a second motor linked to the second sun gear suchthat activation of the clutches, brakes, and motors in a firstcombination places the multi-mode hybrid drive train in a series mode ofoperation, activation of the clutches, brakes, and motors in a secondcombination places the multi-mode hybrid drive train in a parallel modeof operation, and activation of the clutches, brakes, and motors in athird combination places the multi-mode hybrid drive train in a powersplit mode of operation.
 2. The multi-mode hybrid drive train accordingto claim 1, wherein activation of the clutches, brakes, and motors in afirst combination comprises causing the second brake and third brake tobe active to place the multi-mode hybrid drive train in a series mode ofoperation.
 3. The multi-mode hybrid drive train according to claim 1,wherein activation of the clutches, brakes, and motors in a secondcombination comprises causing the first clutch, the first brake, and thesecond brake to be active to place the multi-mode hybrid drive train ina parallel mode of operation.
 4. The multi-mode hybrid drive trainaccording to claim 1, wherein activation of the clutches, brakes, andmotors in a third combination comprises causing the second brake and thefirst clutch to be active to place the multi-mode hybrid drive train ina power split mode of operation.
 5. The multi-mode hybrid drive trainaccording to claim 1, wherein actuation of the first clutch and thesecond clutch places the multi-mode hybrid drive train in a compound CVTmode of operation.
 6. The multi-mode hybrid drive train according toclaim 1, wherein the first motor/generator unit is linked to the firstsun gear, and the second motor/generator unit is linked to the secondsun gear.
 7. The multi-mode hybrid drive train according to claim 1,wherein the first motor/generator unit and second motor/generator unitare electric motors/generators configured to provide rotational energyupon the application of electrical power and to supply electrical powerupon the application of rotational energy.
 8. The multi-mode hybriddrive train according to claim 1, wherein the first planetary gear trainfurther comprises a primary power input for receiving rotational energyfrom a primary power source.
 9. The multi-mode hybrid drive trainaccording to claim 8, wherein the primary power source is one of anengine and a hydraulic motor.
 10. The multi-mode hybrid drive trainaccording to claim 1, further comprising an energy storage system forreceiving electrical power generated by the second motor/generator unit.11. A multi-mode hybrid drive train for selective operation in one aplurality of operational modes, the multi-mode hybrid drive traincomprising: first and second planetary gear sets; a firstmotor/generator input to the first planetary gear set; a secondmotor/generator input to the second planetary gear set; a primary powerinput for receiving power from a primary power source; and a pluralityof clutches and a plurality of brakes, located such that selectiveactivation of the plurality of clutches and plurality of brakes placesthe multi-mode hybrid drive train into one of a series mode ofoperation, a parallel mode of operation, and a power split mode ofoperation.
 12. The multi-mode hybrid drive train according to claim 11,wherein the first planetary gear set includes a first sun gear, firstcarrier and first ring gear, wherein the second planetary gear setincludes a second sun gear, a second carrier connected to a final drive,and a second ring gear, and wherein the first motor/generator input islinked to the first sun gear and the second motor/generator input islinked to the second sun gear, the multi-mode hybrid drive train furtherincluding: a first clutch for selectively clutching the first carrier tothe second carrier and a second clutch for selectively clutching thefirst sun gear to the second ring gear; and a first brake forselectively braking the first carrier, a second brake or selectivelybraking the first sun gear, and a third brake for selectively brakingthe second ring gear.
 13. The multi-mode hybrid drive train according toclaim 12, wherein activation of the clutches, brakes, and motors in afirst combination comprises causing the second brake and third brake tobe active to place the multi-mode hybrid drive train in a series mode ofoperation.
 14. The multi-mode hybrid drive train according to claim 12,wherein activation of the clutches, brakes, and motors in a secondcombination comprises causing the first clutch, the first brake, and thesecond brake to be active to place the multi-mode hybrid drive train ina parallel mode of operation.
 15. The multi-mode hybrid drive trainaccording to claim 12, wherein activation of the clutches, brakes, andmotors in a third combination comprises causing the second brake and thefirst clutch to be active to place the multi-mode hybrid drive train ina power split mode of operation.
 16. The multi-mode hybrid drive trainaccording to claim 12, wherein actuation of the first clutch and thesecond clutch places the multi-mode hybrid drive train in a compound CVTmode of operation.
 17. The multi-mode hybrid drive train according toclaim 12, wherein the first motor/generator unit and secondmotor/generator unit are electric motors/generators configured toprovide rotational energy upon the application of electrical power andto supply electrical power upon the application of rotational energy.18. The multi-mode hybrid drive train according to claim 11, furthercomprising an energy storage system for receiving electrical powergenerated by the second motor/generator unit.
 19. The multi-mode hybriddrive train according to claim 11, wherein the primary power input isconfigured to receive power from one of an engine and a hydraulic motor.20. A controller for controlling a machine transmission, thetransmission including a plurality of clutches and brakes to selectivelyconfigure the transmission for operation in one of a plurality of modesof operation including a series mode of operation, a parallel mode ofoperation, and a power split mode of operation, the controller includingcomputer-executable instructions stored on a computer-readable medium,the computer-executable instructions comprising instructions for:receiving a command indicating a selected mode of operation; andactivating selected ones of the clutches and brakes to configure thetransmission for operation in the selected mode of operation.